Research published this week in Proceedings of the Royal Society B: Biological Sciences solves a mystery that has long shrouded our understanding of white oaks: where did they come from? The approximately 125 white oak species in the Americas and 25 in Eurasia—including the massive bur oak of American prairies and savannas, the valley oak of California and the eponymous white oak of eastern North American forests—are important in forests and savannas throughout much of the northern hemisphere. Yet, despite their economic and ecological importance, not much was known about the evolutionary history of the white oak group until now.